Gene Expression Differences Between Developmental Stages of the Fall Armyworm (Spodoptera frugiperda)

The fall armyworm (Spodoptera frugiperda) is one of the most significant agricultural pests in the world and invaded China in early 2019. We sampled and sequenced RNA-seq data from 15 individuals across different developmental stages. Developmental stages were the larval stage (5th instar larvae and 6th instar larvae), chrysalis stage, and adult stage (female adult and male adult). Individual samples were mainly clustered by developmental stages and we then identified variation between developmental stages of differentially expressed transcripts (DETs). There were 2136 upregulated DETs and 1391 downregulated DETs in the larval stage when comparing larval and chrysalis stages. In the comparison between the chrysalis and adult stages, there were 2033 upregulated DETs and 1391 downregulated DETs in the chrysalis stage. In total, 19,195 abundantly expressed transcripts were obtained and 10% of them were DETs. We then obtained stage-specific DETs to investigate the potential function of the fall armyworm during different developmental stages. We also constructed our annotation background set for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. This indicated that the fall armyworm may undergo active metabolism during its lifespan, even in the chrysalis stage. And it also may experience detoxifying and xenobiotic metabolism throughout its life, especially in the larval stage, which partially explains the difficulty to eradicate using chemical control. Our study is the first insight into the developmental patterns of the fall armyworm and we also provide the fundamental information about enhanced drug resistance at the level of transcriptome. These results are beneficial for a future investigation related to the eradication and/or control stage.